Ultimate Headphone Guide Articles: Headphones and Hearing Safety

Headphones and Hearing Safety
Safety is very important for any hobby involving loud noises. Race fans and gun enthusiasts, for example, require protection to avoid long-term hearing damage. But for the audiophile, sound is the whole point of the hobby. Education, along with some common sense, is essential.

Overexposure to loud volumes has a cumulative effect that damages the ears on a physical level. Hearing a temporary ringing sound after attending a loud concert is a just small glimpse of what could eventually become a permanent condition called "tinnitus". While some types of sensory hair cells inside the ear do have the ability to recover from over-exposure to loud sounds, new research (Kujawa and Liberman, 2009) suggests irreversible damage takes place in other parts of the auditory system. This damage may not manifest until much later and is completely undetectable at first. Years down the road, when the hearing problems actually do surface, there's no way to go back and reverse the process.

It's not easy to tell if headphones are too loud, and in contrast to speakers, even the cheapest headphone can usually play extremely loud, even with modest equipment. Combine this with the delayed symptoms of hearing damage and it's easy to see why headphone users are a particularly high risk demographic. If you value your hearing and plan on enjoying this hobby for many years to come, you'll definitely want to be responsible when it comes to volume levels.

Setting the Volume
The simplest way to set the volume on headphones at a safe level is to slowly turn them down until it's obviously too quiet, then turn it back up a notch or two. Try to resist slowly creeping up the volume over time. Here's an encouraging note: At volume levels above 90dBspl, the small bones of your middle ear begin to automatically tense to limit damage to the inner ear (called the stapedius reflex). This reflex adds both noise and distortion to the music heard. Yes, your music will actually have better sound quality if the volume remains at a moderate level.

Signal to Noise
Open headphones don't offer any isolation. So people tend to listen at louder levels to overcome interference from background noise. Sealed headphones, and particularly noise-cancelling models, should require lower levels to get the same music signal to environmental noise ratio. That doesn't necessarily make them safer in all cases, but it might help for some users.

In-ear monitors are noteworthy in that they require an extra degree of maintenance not needed by larger headphones. Since their tips insert into the ear canal itself, they require cleaning on a regular basis. Use of dirty tips could result in irritation or even infection in some cases. In-ear monitors tend to isolate fairly well but are also very sensitive and thus easier to accidentally play at extreme levels. A good practice is to completely lower volume on the playback device before inserting the monitors, then slowly raise the volume to comfortable levels.

Hearing Tests
Part of being a responsible listener is getting periodic hearing checkups. Most people get yearly eye exams and dental checkups, but surprisingly few bother to test their hearing on a regular basis. The test produces a chart called an audiogram that looks something like a frequency response chart. It's a relatively simple process that can be done by an Audiologist or most hearing aid dispensers. Routine testing makes it easier to spot early signs of hearing loss and make the necessary adjustments to help combat further damage. Larger chains like Costco sometimes offer free testing but it's definitely worth paying for if needed.

Recommended Noise Exposure Limits
UHG_HearingSafety_chartThe National Institute for Occupational Safety and Health (NIOSH) establishes guidelines for how long we can tolerate noise, and at what levels, before putting ourselves at risk. Higher volumes equal shorter allowable exposure time, but it can also be dangerous to play moderate levels for lengthy periods.

COMMENTS
xnor's picture

me posting a link to my attempt at calculating ideal headphone amplifier gain for different headphones and ideal volume control range:

http://www.head-fi.org/t/668238/headphones-sensitivity-impedance-required-v-i-p-amplifier-gain

 

Some numbers are still off a bit but should be roughly ok. As can be seen most headphones need very little power to reach dangerous levels especially with today's dynamically compressed music.

In other words (also concerning the previous article):
given a 2V source, most of the time you don't need any amplification (voltage gain) at all, but clean attenuation.

NA BLur's picture

I figured I would chime in and add that a running lawnmower is about 90dB while a rock concert can be 115dB + which is why it is so important to wear some sort of hearing protection.  Sure it is fun while you are young, but too many concerts and you get to look forward to hearing aids or even deafness.

The folks I run into with the most hearing damage are usually from the military who continue to go to the shooting range and not wear hearing protection.

Signs of hearing loss:

Continuous ringing in the ears especially in the morning

Having to be told to turn down the volume on the TV by your family / friends

Having to be told to turn down the volume on your car stereo

Take a look here for more details:

http://www.starkey.com/hearing-loss-and-treatment/identify-hearing-loss/...

In the end it is more about being smart and preventing hearing loss.

woody's picture

When I see this picture, I don't think about hearing damage, instead, I am thinking that perhaps Tyll is trying to tell us that the HD800s sounds like crap. Well, do they, Tyll? ;)

Tyll Hertsens's picture

They're good...but you gotta work on it.

veggieboy2001's picture

Great article Tyll! (I think the picture is hilarious) Very important info....more people should hear this message (pun intended). Hopefully one day we'll be able to fix hearing damage, but until then, sensible listening habits can't be overstressed.

Lawk's picture

I got tinnitus after a whiplash type neck injury several years ago.

It sounds like some sort of electrical storm. Funnily this noise in my head got me involved with headphones in the first place. There is no cure and no escape. But within the music it sort of fades away. I have learned to deal with it. But it was very hard at first.

Initially I didn't even tie it to hearing. There is some literature showing how somatosensory inputs from the upper cervical region feed into the auditory system at the dorsal cochlear nucles in the brainstem.

the truth is there isn't much going on in my right ear beyond 13khz. So my hypothesis goes, I probably had it to some degree before. But with the decreased activity coming from the auditory nerve and ear, the dorsal cochlear nucleus tries to compensate by reducing inhibition, like upping its gain and this somehow also amplifies the somatic information flow, which is abnormal anyway due to my snapped neck stuff.

Something like that. But it isn't just me and scifi:

up to 70% of people with tinnitus can modulate their tinnitus by clenching their jaw, pressing on their neck, flexing neck muscles, even tounge movement.

There is also something called gaze-evoked tinnitus which is associated with eye movement.

Anyway moral of the story; the ear might be the first peripheral damage, the hair cells. But the noise itself is then generated by the brain itself, in a an unproductive compensating mechanism. (apparently not always, some people with hearing loss do not get tinnitus).

It is very unfortunate that so little money is spent on research. But so many are affected, I think it costs the US veteran system billions since so many come back from war zones with the unwanted guest in their head.

Speaking of unwanted guest; the absolute best way to deal with it, should you ever get it, is to accept it. The process is called habitution.

One last thing to note; Hearing tests generally only go up to 8khz or 10khz, rarely 12khz. So often you are told "everything is in order" when the party only goes to shit when you go beyond 10khz.

Tyll Hertsens's picture

Interesting post, thanks.

Seth195208's picture

...starts distorting above 90db, why test thd in headphones at 90 and 100db? Wouldn't it make more sense(And be more responsible:) to test at 80 and 90db? 

xnor's picture

An average SPL of 80 dB can still mean that there will be peaks above 90 dB SPL. If you're into clean sound reproduction, i.e. not using a tube amp with high THD, you probably want those peaks to be reproduced without a crazy rise in distortion (see 100 dB test)

And I guess that lowering the SPL would make the noise component significant. 0.1% means -60 dB, so if you test at 80 dB the noise floor needs to be quite a bit below 20 dB SPL.

Seth195208's picture

Both the dynamic range and noise floor explanations make total sense. Thanks for the response.

Tyll Hertsens's picture

xnor's answer is most of it. Also, I think it's important to test stuff at levels that push them a bit to see if they remain well behaved near the operating limits. As xnor indicated, musical peaks at even moderate levels might occasionally hit 100dB, so it's not an unrealistic level.

funkmeister's picture

I personally listen at very quiet levels comparatively. I've been very conscious, even as a kid, to not listen loudly. Headphones are weird in that they can totally trick you more than speakers into listening too loud.

I'd love to see something that shows numbers for measurements in the 70's of decibels.

xnor's picture

Exactly! When you turn up a cheap stereo you will hear a crazy increase in distortion, and bass output will be limited. These are characteristics of a cheap stereo but will be interpreted as: "man, that's loud."

Turn up cheap in-ears to 110 dB SPL and sound will still be reproduced fairly distortion-free.

There's also the whole problem of visceral bass impact that you don't get with headphones. Some people seem to (partly) compensate for that with higher volume. sad

Dan S's picture

Thanks as always for these great articles, Tyll! I think it's awesome that you're including an article about hearing safety in your guide.

An addition I'd like to see is how to measure how loudly I'm listening.

When I look at a table like your "Recommended Noise Exposure Limits" above, my feeling is, okay, good to know that at 85 dB I can listen for 8 hours, and at 91 dB I can listen for 2 hours. But how am I going to use this information?

Without a practical method to measure how loudly I'm listening, that table isn't really all that useful. For someone who wants to be careful about their hearing, I'd like to understand what the next step is beyond "slowly turn them down until it's obviously too quiet, then turn it back up a notch or two." Is there something I can buy at Radio Shack to measure the volume?

If there is, mentioning it probably wouldn't use up too many words, and it could be very helpful. Thanks!

Tyll Hertsens's picture

I've heard of folks putting the Radio Shack sound pressure level meter mike through a piece of cardboard and then putting the cans up against the cardboard. I think this might work okay.  It's a simple experiment, I should do it and report back.

Dan S's picture

Thanks, Tyll!

I listen to music at work most of the day at a fairly consistent volume, as others probably do, so it's great to know what the potential impact is.

Your experiment sounds like great fodder for an article!

davidsh's picture

From what I have read so far, it seems the iphone with the correct spl app is fairly accurate within some decibels compared to actual spl meters.

NightFlight's picture

I had a sudden concern with Tyll's shout-out for hearing safety. It's been something in the back of my mind and as an audiophile I'm always concerned about potential hearing damage. I've had a few close calls with hearing losss due to my own supidity and those around me. But I digress...

What I really wanted to say is that I wouldn't put too much stake in SPL/DBA measurement apps that run on portable devices. I very quickly determined that my Google Nexus taps out at 86SPL. That would vary from App to App one maxing out at 96db. I'm certain I know what 110-115db sounds like (I don't go there very often, or for long) and I found all the apps I tested fell short by around 20db.

Initially I was quite pleased with myself thinking that my extened listening levels were quite acceptable.  But that may be completely wrong and I'm heading out today to find a proper SPL calibrated device at Radio Shack. While still not a professional device - certainly better than any 'App' by a wide margin.  You might balk at the expense vs a free App. Then again, we are talking about our hearing right?. Just how much is that worth to you? The answer should be - more than all the high end equipent you might buy. Those are just toys.